GB2500713A

GB2500713A - Solar heating system including a heat pump

Info

Publication number: GB2500713A
Application number: GB1205763.4A
Authority: GB
Inventors: Adrian Musgrove
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-03-30
Filing date: 2012-03-30
Publication date: 2013-10-02
Also published as: GB201205763D0

Abstract

The solar heating system comprises at least one solar collector 1 and at least one heatable device 2. A fluid transport loop conveys a fluid from the solar collector(s) to the heatable device(s) by a supply conduit 3, and back again by a return conduit 4. A first 8 and second 6 heat exchanger are in thermal communication with the supply and return conduit respectively. The first and second heat exchangers are linked via a heat pump 9 so as to facilitate extraction of thermal energy from the fluid at the second heat exchanger and reintroduction of thermal energy to the fluid at the first heat exchanger. The heatable device(s) may comprise a hot water tank or a central heating radiator (2, figure 1), or alternatively a turbine or heat engine 11 that provides power to the heat pump. Use of the heat pump increases the thermal efficiency of the system since the fluid is very cold when returning to the solar collector(s) and very hot when entering the heatable device(s).

Description

A SOLAR HEATING SYSTEM

Field of the Invention

The present invention relates to heating systems, such as domestic central heating systems, which utilise solar energy to heat fluid within the system.

Background of the Invention

Increasing energy costs and environmental concerns have lead to the adoption of alternative energy systems in a wide range of applications. The use of solar collectors that make use of the sun's energy is one such alternative energy approach.

Solar collectors, such as solar panels, are increasingly being used on both commercial and domestic buildings to capture the sun's energy by heating a fluid as it circulates through the collector. This heated fluid can then be used to supp'ement the heating requirements of the building, thereby reducing the reliance on traditional energy such as gas or electricity to heat the building.

In high solar energy conditions these systems will transfer heat from the collector direct to a heating device which would usually use traditional energy.

Typically these heating devices could be a hot water storage tank or a heat radiator.

In lower solar energy conditions, such as on a cloudy day, the temperature of the fluid exiting the solar collector can be reduced and may sometimes be so low as to deliver little or no heating effect to the heating device.

There is a need for a more efficient solar heating system that can maximise the levels of solar energy captured by the solar collectors in rower solar energy conditions, whilst at the same time maximising the heating effect delivered to the heating device.

Summary of the Invention

The present invention seeks to provide an improved and more efficient solar heating system suitable for use in the central heating systems of both commercial and domestic buildings.

The present invention provides a solar heating system according to claim 1.

The improvement in the efficiency of the solar heating system of the present invention is two-fold.

Firstly, by extracting thermal energy from the fluid returning to the solar collector from the heatable device using a heat exchanger it is possible to lower the temperature of the fluid entering the solar collector. It will be appreciated that by reducing the thermal energy level of the fluid supplied to the solar collector it is possible to increase the capacity of the fluid to capture solar energy as it flows through the solar collector.

Secondly, by using a combination of the heat pump and the heat exchanger it is possible to use the thermal energy extracted in the first instance to supplement the thermal energy already present in the fluid flowing from the solar collector to the beatable device and thereby increase the heating effect of the fluid on the heatable device.

Preferably the system may further comprise at least one thermal transfer loop that facilitates the flow of a thermal transfer fluid between the first and second heat exchangers via the heat pump.

Preferably the system may further comprise a pump to circulate the fluid within the fIud transport loop.

Preferably the solar collector may comprise an outlet connected to the supply conduit and an inlet connected to the return conduit.

Preferably the heatable device may comprise an inlet connected to the supply conduit and an cutlet connected to the return conduit.

Preferably the beatable device may be selected from the group consisting of a heater radiator, a hot water storage tank, a turbine and a heat engine.

1-lowever other suitable devices capable of utilising the flow of heated fluid from the solar collector will be apparent upon consideration of the full

disclosure of the present invention.

Advantageously said at least one heatable device may be a turbine or a heat engine that supplies power to the heat pump and/or the fluid transport loop pump. En this way the solar energy captured by the collector can be used to help power the system, thus reducing the Level of traditional energy required.

Preferably the fluid in the fluid transport Loop may comprise water. It is appreciated that the high specific heat capacity of water makes it suitable for use as the fluid. However other fluids with high specific heat capacities are also considered appropriate.

Advantageously the fluid in the fluid transport loop may comprise additional additives in the form of corrosion inhibitors and/or anti-freeze.

Preferably the thermal transfer fluid may comprise a refrigerant. Any commercially available refrigerant may be used.

Preferably the system may further comprise one or more one way valves to ensure a one directional flow of fluid within the loop.

Preferably the fluid transport loop may comprise at least one temperature sensor to monitor the temperature of the fluid at least one location within the loop.

The present invention also provides a method of improving the efficiency of a solar heating system according to claim 14. -3..

Preferably the method may further comprise providing a first heat exchanger to impart thermal energy on the fluid in the fluid transport loop and providing a second heat exchanger to extract thermal energy from the fluid in the fluid transport loop, said heat exchangers being linked by the heat pump.

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Preferably the method may further comprFse using said heatable device, preferably in the form of a turbine or heat engine, to generate electricity to power the heat pump.

Brief Description of the Drawings

The present invention will now be described with reference to the preferred embodiments represented in the drawings, wherein: Figure 1 shows a flow diagram of a first embodiment of the solar heating system of the present invention; and Figure 2 shows a flow diagram of a second embodiment of the solar heating system of the present invention.

Detailed Description of the Preferred Embodiments

The present invention provides a solar heating system that is considered particularly suitable for use in both domestic and commercial properfies to at least supplement, and possibly replace, the heating systems of such properties and thereby reducing the levels of traditional energy sources, such as electricity and gas, used.

The present invention will now be described with reference to the two preferred embodiments of the solar heating system represented in the figures.

Referring first to figure 1, which provides a flow diagram a first preferred embodiment of the heating system, it can be seen that a solar collector 1 is linked to a heatable device 2 via a fluid transport loop.

An outlet of the collector 1 is linked to an inlet of the heatable device 2, which in a basic system could be a domestic heat radiator, by supply conduit 3. An outlet of the heatable device 2 is then looped back to an inlet of the collector 1 by a return conduit 4.

It is appreciated that the dimensions of the supply and return conduits 3, 4 will to an extent be determined by the heat capture capacity of the solar collector 1. Suitable conduits will therefore be appreciated by the skilled person upon consideration of the present application.

Together the supply conduit 3 and the return conduit 4 form the fluid transport loop that facilitates the continuous circulation of a fluid, which is preferably water due to its high specific heat capacity, between the collector 1 and the

heatable device 2.

The system is provided with at least one pump 5 to assist the flow of the fluid around the loop. It is appreciated that the fluid transport loop may also comprise one or more one-way valves (not shown) to ensure the fluid always flows in the same direction The system is also provided with a first heat exchanger 8 and a second heat exchanger 6. The first heat exchanger 8 is positioned in thermally conductive association with the supply conduit 3 of the fluid transport loop. The second heat exchanger 6 is positioned in thermally conductive association with the return conduit 4 of the fluid transport loop.

When describing the heat exchangers as having a thermally conductive association it is to be understood that the arrangement of the heat exchanger relative to the fluid transport loop is such that thermal energy can be transferring either into or out of the loop by the appropriate heat exchanger.

Suitable heat exchange interfaces will be readily appreciated by the skilled person upon consideration of the present invention.

Positioning the second heat exchanger 6 in association with the return conduit 4 facilitates the extraction of thermal energy from the fluid in the loop as it returns to the collector 1 from the heatable device 2.

Positioning the first heat exchanger 8 in association with the supply conduit 3 facilitates the reintroduction of thermal energy into the fluid in the loop before it arrives at the beatable device 2 from the collector 1.

According to the embodiment of the system represented in figure 1, in order to enable the thermal energy extracted by the second heat exchanger 6 to be reintroduced by the first heat exchanger 8 the exchangers are linked by two fluid transfer loops 7 and 10, which are in turn linked via a heat pump 9. The fluid transfer oops preferably contain a compressible fluid with a low boiling point in the form of any commercially available refrigerant heat pumps, such as the heat pump 9 used in the present invention, are well known for their ability to move thermal energy up an energy gradient (i.e. from a lower energy location to a higher energy location).

In the present invention the operation of the heat pump enhances both the extraction of thermal energy from return conduit 4, by providing a cooled thermal transfer fluid to the second heat exchanger 6, and the reintroduction of thermal energy Ento the supply conduit 3 by pumping' the thermal energy up an energy gradient into the heated fluid coming from the collector 1.

Figure 2 shows an alternative arrangement wherein the system is provided with more than one heatable device. Whilst the system retains a heatable device in the form of a radiator 2, it is also provided with a device 11 that is capable of harvesting energy from the thermal energy in the circulating fluid. It is appreciated that the device 11 could also be utilised in the system represented in figure 1.

It is appreciated that suitably the device 11 may take the form of a turbine or a heat engine. Such devices, it is appreciated, are capable of generating power that can be used to run the heat pump 9 via linking means 12. The linking means may be mechanical or electrical. It is also envisaged that such device 11 could be used to help power the pump 5 which assists the circulation of fluid within the fluid transport loop.

It is also appreciated that the heat engine or turbine could be linked to an energy storage device, which stores energy in the form of electricity or alternatively compressed air. In this way any excess energy collected by the system can be collected and stored for a later time.

Although not shown, it is appreciated that the system of the present invention may be provided with one or more temperature sensors that monitor the temperature of the fluid within the fluid transport loop. These sensors could be linked to a control unit (also not shown) which can operate the pump 5 and heat pump 9 accordingly.

In order to further explain the present invention the operation of the solar heating system of the present invention will now be described in more detail.

The solar collector 1, which may typically consist of an array of solar panels located on the roof of a building, captures energy from the sun as it shines.

The solar collector is provided with a system of pipe work through which a fluid, such as water, can flow. As the fluid flows through the solar collector I it is gradually heated by the sun.

When the fluid leaves the solar collector 1 it contains more thermal energy and is thus hotter that when it entered the solar collector. This heated fluid A then flows via the supply conduit 3 to the heatable device 2. However, before the fluid A reaches the device 2 it passes by heat exchanger 8, at which point additional thermal energy is imparted to the fluid thereby providing further heated fluid B which has an increased temperature to that of fluid A. Fluid B arrives at the heatable device 2 wherein it imparts thermal energy to the device, the level of which will depend on the nature of device. It is noted for example in the case of a heat radiator that on days when central heating is not required the radiator may use minimal energy. In these situations the thermal energy may be captured and stored as described above.

Fluid C exits the device 2 cooler that it entered it due to the transfer of its thermal energy to the device 2. However it is appreciated that the fluid C will still contain thermal energy. It is therefore the role of heat exchanger 6 to extract additional thermal energy from fluid C before it returns to the collector 1.

The extraction of this additional thermal energy from fluid C by the heat exchanger 6 further lowers the temperature of the fluid such that fluid D returns to the collector with a much greater capacity to absorb thermal energy fromthesun.

The system of present invention is made more efficient by maximising the thermal energy difference between fluid A and fluid D so that even on [ow solar energy days thermal energy is effectively captured by the solar collector 1.

In is appreciated that while the solar heating system of the present invention may be use on its own, it could also be used in combination with a traditional heating system to reduce its reliance on traditional energy sources such as gas and electricity.

As a further aspect of the present invention it is appreciated that, at such times as may be considered appropriate (e.g. at night), the pump 5 can be operated with the heat pump 9 off (or even operating in reverse) so that thermal energy collected by radiators can then be transported back to the collector 1. lt is appreciated that this action will cool the interior of the building where the radiator is located, which may be beneficial especially in hot weather.

Also. it is appreciated that in extreme cold weather conditions snow and ice may accumulate on the collector 1, which can result in a large reduction of the efficacy of the system because the white coloured snow will reflect a large proportion of the solar energy. In such situations, once again operating the pump 5 with the heat pump 9 off (or operating in reverse) will serve to melt the reflecting ice and permit the collector to operate at optimum efficiency again.

Claims

Claims 1. A solar heating system comprising: at least one solar collector and at least one beatable device; a fluid transport loop that facilitates the flow of a fluid from said solar collector to said heatable device via a supply conduit and back again via a return conduit; a first heat exchanger having a thermally conductive association with the supply conduit of the fluid transport loop; a second heat exchanger having a thermally conductive association with the return conduit of the fluid transport loop; and wherein the first and second heat exchangers are linked via a heat pump so as to facilitate the extraction of thermal energy from the return conduit via the second heat exchanger and the reintroduction of themial if energy into the supply conduit via the first heat exchanger.
2. The solar heating system of claim I further comprising at]east one thermal transfer loop that facilitates the flow of a thermal transfer fluid between the first and second heat exchangers via the heat pump.
3. The solar heating system of claim 1, further comprising a pump to circulate the fluid within the fluid transport loop.
4. The solar heating system of claim 1,2 or 3, wherein said solar collector comprises an outlet connected to the supply conduit and an inlet connected to the return conduit.
5. The solar heating system of claim 1, 2, 3 or 4, wherein said heatable device comprises an inlet connected to the supply conduit and an outlet connected to the return conduit.
6. The solar heating system of any of claims 1 to 5, wherein said heatable device is selected from the group consisting of a heater radiator, a hot water storage tank, a turbine or a heat engine.
7. The solar heating system of any of claims 1 to 6, wherein said at least one beatable device comprises a turbine or a heat engine that supplies power to the heat pump and/or the fluid transport loop pump.
8. The solar heating system of any of claims 1 to 7, wherein the fluid within the fluid transport loop comprises water.
9. The solar heating system of any of claims 1 to 8, wherein the fluid within the fluid transport loop comprises additives in the form of corrosion inhibitors and/or anti-freeze.
10. The solar heating system of any of claims Ito 9, wherein the thermal transfer fluid comprises a refrigerant.
11. The solar heating system of any of claims ito 10, further comprising one or more one way valves to ensure a one directional flow of fluid within the system.
12. The solar heating system of any of the preceding claims, wherein the fluid transport loop comprises at least one temperature sensor to monitor the temperature of the fluid at least one location within the loop.
13. A central heating system for a building comprising the solar heating system of any of the preceding claims.
14. A method of improving the efficiency of a solar heating system having at least one solar collector linked to at least one heatable device by a fluid transport loop and a heat pump, said method comprising: extracting thermal energy from the fluid in the transport loop at a location downstream of said beatable device but upstream of said solar collector thereby reducing the temperature of the fluid supplied to the solar collector; imparting thermal energy on the fluid in the transport loop at a location upstream of the beatable device but downstream of said solar collector thereby increasing the temperature of the fluid supplied to the heatable device; and operating the heat pump to increase the levels of thermal energy extracted from and imparted to the fluid in the transport loop.D
15. The method of claim 14, further comprising providing a first heat exchanger to impart thermal energy on the fluid in the fluid transport loop and providing a second heat exchanger to extract thermal energy from the fluid in the fluid transport loop, said heat exchangers being linked by the heat pump.TO
16. The method of claim 14 or 15, further comprising using said heatable device, preferably in the form of a turbine or heat engine, to generate electricity to power the heat pump.
17. The method of any claims 14 to 16 carried out using the solar heating system of any of claims 1 to 12.
16. A solar heating system substantially as described, with reference to the drawings, herein before.
19. A method of improving the efficiency of a solar heating system substantially as described, with reference to the drawings, hereFn before.